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'51 Chieftain - On The Road


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Last night I dismantled the valve block, and I'm glad I did.

A fair bit of band dust had collected in the bores and the valves weren't smooth to operate. 

I had avoided rubbing the valves down last time, but there were a few burrs and nicks on the valves that were causing them to get hung up, so those were very carefully removed with high grit paper.

 

I reassembled it all and now it's ready to go back in.

The truth will be in the way it drives.

 

Phil

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Filled the gearbox up and went for a drive.

It mostly behaves very well as in the video but occasionally it doesn't. One thing it did, which was a lightbulb moment was to engage the parking pawl going into reverse. That should only happen when there's no oil pressure so next port of call is the pressure regulator to check it's not sticking.

 

Phil

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I pulled the regulator out and it's good, the gears tend to get hung up after being in neutral or reverse.

 

I'm going to completely strip it down and flush it all though again. I'll get to the bottom of it, there a couple valves I didn't pull (stupid).

 

Phil

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Today, ahead of the bad weather I decided to take the car to work.

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Also got the correct thermal type turn signal flasher relay from Napa. 

 

Now it's all boarded up inside the garage.

 

Weather eye on the horizon again.

 

Phil

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55 minutes ago, john hess said:

Looks like the mural was safe also... Stay positive... Things can be repaired and replaced. Just glad you and family are ok..

Yeah, both Chieftains survived.

The house and everybody in it is good, which is the main concern.

 

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A little trip to town to clear my head and get provisions.

 

It's running better now though the gearbox is still getting hung up. 

 

Once I've finished with the house I'll get back on the car and pull the valve block out again.

 

Phil

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On 10/14/2020 at 2:43 PM, Summershandy said:

Hey Phil! This just came up on a buy and sell just 3 hours from me. They're asking $2,000 USD. That's about what these project cars go for around here. 

Saw it and thought of you.....no info on the engine condition. 

Mark

 

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This is a Canadian Pontiac. It's barely a cousin to the Chieftain. It's a Chev body with a Pontiac dash and grille, and a 6 cyl Pontiac engine. 

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One horn done. 

 

Gearbox is being a pain again. I've isolated the behavior- 2 patterns with a common denominator so I ordered a gauge that'll read the oil pressure at the test point on the gearbox so I can run through the diagnostics in the manual and try determine cause.

 

Phil

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On 10/23/2020 at 6:04 AM, PhilAndrews said:

I had avoided rubbing the valves down last time, but there were a few burrs and nicks on the valves that were causing them to get hung up, so those were very carefully removed with high grit paper.

 

Don't do that! I wish I had seen this earlier. The sharp edges on automatic transmission spool valves are essential to their operation. If you took the edge off, even a little, you most likely need another valve body.

 

Spool valves do need to be clean, and need be able to fall out of the bore under their own weight. I may not be obvious looking at them, but in operation they are balanced, in other words a stiff spring would be completely balanced by hydraulic pressure on the other side of the valve. The pressure imbalance needed for one to move under operating conditions is tiny. Don't fall into the trap of thinking since there is a big spring in there it takes a bunch of pressure to move the valves in normal operation. It doesn't.

 

One tiny speck of dust in an automatic can wreak unbelievable havoc. Most of the crud from linings winds up in the pan and stays there but not all of it. The sharp edges and extremely close clearances of the spool valves allow them to push tiny particles out of the way, rather than getting one caught under the edge.

 

Don't use sandpaper or wire wheels or anything like that. Assemble it in a CLEAN area on a CLEAN bench. If you have to do it in your garage, shut all the doors, shut off all the fans and wet down the floors. NO SHOP RAGS. The lint will cause the valves to stick. Clean each part in clean solvent, or brake clean, blow dry with compressed air, dunk in clean transmission fluid, then put in.

 

If the manual specifies torque for the bolts holding the valve body together or to the transmission (probably) then follow the specs. Uneven or wrong tightness can cause the bores to distort enough for the valves to stick even if they are fine on the bench.

 

Good luck, and let us know how it turns out.

 

 

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What I took off is on the leading edge, leaving as much of the 90 degree of the valve intact as remains. 

 

It looks like it's possibly been dropped.

 

I haven't put any abrasives on the machine faces.

 

I wasn't clear enough but thank you for the warning, not a lot of people know and ruin the valve and bore.

 

All the fixings are torqued to spec.

 

I'll probably end up needing another valve block and valves, this one is.. worn.

 

Phil

Edited by PhilAndrews (see edit history)
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Further to that, yes. The valves do slide out under their own weight on both sides. I matched the governor plungers to the best bore as suggested in the book; the 1-2 bore has a couple of high points as evidenced by the witness marks. They are helical so part of the casting rather than being scored.

I'm surprised the damage isn't worse, considering how much in the way of metal particles were inside the system.

 

The failure is 1st gear holds for much higher road speed than it should per throttle position after the gearbox is put into either N or R; it will then change violently into 3rd and then be reluctant to engage 4th.

If you slow down before it engages 4th, it'll change back down 3-2-1 and then replay the high speed (15mph or thereabouts) 1-3 gear thump over and over. 

The speed at which it changes 1-3 is critical, and throttle position has no bearing on it. Snapping the throttle shut will not make it change up, only road speed.

 

Once it's engaged 4th, so long as the shifter remains in Dr, it'll cycle through the gears smoothly at the speed you'd expect from the throttle position.

 

4-3 kickdown operates correctly and does not impact gear changes after it's been used.

 

No gears slip. It'll happily squat the back end down and leave 2 pale tire tracks up the street if you stamp on the gas from a standstill, through 1st and 2nd.

 

Occasionally R will engage the parking pawl if you aren't at a complete halt, rather than the cone only engaging, then the pawl coming in once the gearbox has become stationary. By general habit I try not to change the position of the shifter until the car is fully at a rest, was just taught that way.

 

Some of the symptoms feel like a sticking gear selection valve, but some hark of low line pressure. I'm not 100% sure the compensator valve isn't getting stuck.

 

Gauge should be here by close of work tomorrow, I'll have to get an extension piece to fit it. I will run the road tests as outlined in the book and see if it's regulating within spec.

 

Front pump is NOS. Rear pump is original to the engine but wasn't in bad shape. Regulator is existing to the gearbox, TV valve shuttle and pressure relief plunger move smoothly in the pump bore.

 

Phil

Edited by PhilAndrews (see edit history)
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Test tonight per the book. Regulates steadily at 60psi. In gear, pressure rises to about 100psi at full throttle. Off throttle in 4th slowing down, stable 60psi.

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Reverse, a brief dip to 45psi then up to a wobbly 130-150psi as the reverse high pressure comes in and the valve shuttles to regulate.

 

I got it to misbehave one time, and the pressure was stable at 60psi, modulated with throttle position.

 

I can pump it up to 60psi easily on the starter too, so it's making good low speed pressure. Forgot to do rear pump pressure test, I'll do that when it's light tomorrow.

 

So, that does narrow it down to the 1-2 valve sticking. 

 

Phil

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Had a look at the valves today.

 

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They're pretty worn. The valve body is too. Found a couple high points causing trouble. Works better now but I'll probably pull it again and rework it. Didn't want to go hog-wild and cause more trouble than I was fixing.

Really it needs one that's got fewer miles on.

 

Phil

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4 hours ago, Oldtech said:

You are doing quite a job here.  It's too bad they don't have a real filter on these, the screen is so -so. 

Yeah, the brick-catcher is not much use other than stopping the biggest chunks from being drawn in.

 

Phil

Edited by PhilAndrews (see edit history)
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Went for a drive today to the grocery store to see how it would behave.

For the most part, very well. It got hung up one time after sitting in traffic waiting to make a left. 

I think I can improve on that, the bore for the 1-2 valve is not as clean as it should be in terms of surface.

 

Phil

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1 hour ago, Kornkurt said:

Anybody else with this problem, I have a 1953 Dual-range Hydramatic from 60,000 mile car.  

Fluid looks and smells good.  $350 & actual shipping.  Kurt 641-648-9086

 

Please correct me if I'm wrong but the main change on the dual-range was just the control hydraulics, right?

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6 minutes ago, Kornkurt said:

Dual Range came out in 1952 and had 4 speeds.  The nice part is engine braking in 3rd gear for hills and mountains.  I don't know what changes were done to make it Dual Range.

I have a feeling that was the primary change made- the standard Hydramatic, if so fitted, is physically able to do things like 3rd gear hold.

It's nice that they decided to develop it a little and reply to customer requests.

 

For in the flat around here, the regular Hydramatic works well, I could see where 3rd gear hold would be useful. 2nd gear is too much of a jump down for holding speeds where there's any kind of traffic behind you.

 

Phil

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